Chapter 2

Functional Anatomy of Prokaryotic and Eukaryotic Cells

• Comparing prokaryotic and eukaryotic cells– Prokaryote comes from the Greek words for

prenucleus.– Eukaryote comes from the Greek words for

true nucleus.

Prokaryotic Cells

Prokaryote Eukaryote• One circular

chromosome, not in a membrane

• No histones

• No organelles

• Peptidoglycan cell walls

• Binary fission

• Paired chromosomes, in nuclear membrane

• Histones

• Organelles

• Polysaccharide cell walls

• Mitotic spindle

• Average size: 0.2 -1.0 µm 2 - 8 µm

• Basic shapes:

Figures 4.1a, 4.2a, 4.2d, 4.4b, 4.4c

Figure 4.5

• Unusual shapes– Star-shaped Stella– Square Haloarcula

• Most bacteria are monomorphic

• A few are pleomorphic

Arrangements• Pairs: Diplococci,

diplobacilli

• Clusters: Staphylococci

• Chains: Streptococci, streptobacilli

Figures 4.1a, 4.1d, 4.2c

Glycocalyx• Outside cell wall• Usually sticky• A capsule is neatly organized• A slime layer is unorganized

and loose• Extracellular polysaccharide

allows cell to attach• Capsules prevent

phagocytosis

Figure 4.6a–b

Flagella• Outside cell wall

• Made of chains of flagellin

• Attached to a protein hook

• Anchored to the wall and membrane by the basal body

Figure 4.8a

Flagella Arrangement

Figure 4.7

Figure 4.8b

Motile Cells

• Rotate flagella to run or tumble

• Move toward or away from stimuli (taxis)

• Flagella proteins are H antigens (e.g., E. coli O157:H7)

Motile Cells

Figure 4.9

Motile Cells

Figures 4.9a, 4.23d

Axial Filaments• Endoflagella• In spirochetes• Anchored at one end

of a cell• Rotation causes cell

to move

Figure 4.10a

• Fimbriae allow attachment

• Pili are used to transfer DNA from one cell to another

Figure 4.11

Cell Wall• Prevents osmotic lysis

• Made of peptidoglycan (in bacteria)

Figure 4.6a–b

Peptidoglycan• Polymer of disaccharide

N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

• Linked by polypeptides

Figure 4.13a